In general, a bill processing apparatus, which is one of the embodiments of the paper sheet processing apparatus, is incorporated into a service device such as a game medium rental machine installed in a game hall, a vending machine or a ticket-vending machine installed in a public space, or the like which identifies the validity of a bill inserted from a bill insertion slot by a user and provides various types of products and services in accordance with a value of the bill having been judged as valid.
Such a bill processing apparatus comprises, for example, a bill conveyance mechanism which conveys a bill inserted into a bill insertion slot, authenticity judgment means for reading information on the bill being conveyed and judging the authenticity of the read bill, and a bill housing part in which bills judged as being legitimate by the authenticity judgment means are housed, as disclosed in Patent Reference 1. In such a bill processing apparatus, a conveyance speed by a bill conveyance mechanism thereof which conveys the bill is controlled to be constant, and therefore, it is considered that the possibility that a bill judged as being legitimate in an authenticity judgment process is drawn out by a fraudulent activity is not necessarily low.    [Patent Reference 1] Japanese unexamined utility model application publication No. H06-42857